d8d7af15ce
As part of deprecating support for native extensions we are also
migrating away from legacy VM-specific `native 'name'` syntax
towards metadata based encoding which does not require any special
syntax.
This CL is a step 1 in migration:
- introduces support for `@pragma('vm:external-name', 'name')`
which serves as a direct replacement for `native 'name'`;
- all core libraries and tests are migrated to use the annotation;
Once this CL lands and rolls we will edit internal and external embedders
to eliminate uses of the native keyword (step 2) and finally remove
support for native keyword across our parsers (step 3).
TEST=ci
Bug: https://github.com/dart-lang/sdk/issues/28791
Change-Id: Id6dea878db82dd4fd81149243c425b5c5dc6df86
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/212461
Commit-Queue: Slava Egorov <vegorov@google.com>
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
3 KiB
VM-Specific Pragma Annotations
Pragmas for general use
These pragmas are part of the VM's API and are safe for use in external code.
| Pragma | Meaning |
|---|---|
vm:entry-point |
Defining entry-points into Dart code for an embedder or native methods |
vm:never-inline |
Never inline a function or method |
vm:prefer-inline |
Inline a function or method when possible |
vm:notify-debugger-on-exception |
Marks a function that catches exceptions, making the VM treat any caught exception as if they were uncaught. This can be used to notify an attached debugger during debugging, without pausing the app during regular execution. |
vm:external-name |
Allows to specify an external (native) name for an external function. This name is used to lookup native implementation via native resolver associated with the current library through embedding APIs. This is a replacement for legacy VM specific native "name" syntax. |
Unsafe pragmas for general use
These pragmas are available for use in third-party code but are potentially unsafe. The use of these pragmas is discouraged unless the developer fully understands potential repercussions.
| Pragma | Meaning |
|---|---|
vm:unsafe:no-interrupts |
Removes all CheckStackOverflow instructions from the optimized version of the marked function, which disables stack overflow checking and interruption within that function. This pragma exists mainly for performance evaluation and should not be used in a general-purpose code, because VM relies on these checks for OOB message delivery and GC scheduling. |
Pragmas for internal use
These pragmas can cause unsound behavior if used incorrectly and therefore are only allowed within the core SDK libraries.
| Pragma | Meaning |
|---|---|
vm:exact-result-type |
Declaring an exact result type of a method |
vm:recognized |
Marking this as a recognized method |
Pragmas for internal testing
These pragmas are used for inspecting or modifying internal VM state and should be used exclusively by SDK tests.
They must be enabled with the --enable-testing-pragmas flag.
The names of these pragmas are prefixed with "testing".
Additionally, they are categorized into "safe" and "unsafe" forms: "safe" pragmas should not affect the behavior of the program and can be safely added anywhere, whereas "unsafe" pragmas may change the code's behavior or may cause the VM to crash if used improperly.
| Pragma | Meaning |
|---|---|
vm:testing.unsafe.trace-entrypoints-fn |
Observing which flow-graph-level entry-point was used when a function was called |